1. Field of Invention
This invention is directed to a work string jar which is capable of applying an upward or downward jarring force on a work string used in oil or gas wells.
2. Description of Related Art
Double acting jars are known in the prior art however they have certain drawbacks. A known double acting jar is disclosed in U.S. Pat. No. 5,624,001. This jar requires two sets of Belleville spring stacks which add to the complexity and length of the jar. The high pressure seals within the tool are exposed to the drilling mud which can cause premature failure due to the corrosive and abrasive nature of the drilling mud. Furthermore each of the pressure pistons requires an orifice and a check valve. Also this prior art jar does not include a trigger sleeve which reduces wear on the collet and release mechanism.